1. Field of the Invention
The present invention relates to a safety apparatus in industry. More particularly, the present invention relates to a chemical-liquid controlling apparatus.
2. Description of the Related Art
A variety of chemical liquids are used in industry in order to meet different industrial requirements. In order to facilitate different process and different equipment in the factories, various types of automatic chemical-liquid supplying apparatus are produced accordingly to meet demands for low cost and high productivity.
In industry, a common chemical-liquid supplying apparatus includes a container used to contain chemical liquids, a chemical-liquid inlet pipe, and a chemical-liquid outlet pipe. Moreover, in order to prevent the chemical liquid of the container from pollution by air moisture and impurities, a nitrogen gas is supplied to flow through above the chemical liquid in the container, while an exhaust apparatus is operated. The nitrogen gas and the chemical gas volatilized from the chemical liquid are exhausted through an exhaust pipe to flow away from the container. In addition, a high-level sensor and a low-level sensor are mounted at different heights in the container, so as to sense the liquid level and transmit signals. In this manner, a chemical-liquid refilling process can automatically resupply chemical liquid into the container.
While the chemical liquid is used, the chemical liquid is supplied though the chemical-liquid inlet pipe. Once the liquid level decreases to a low level, the low-level sensor transmits a signal, so as to refill automatically the chemical liquid. When the refilling chemical liquid reaches a high level, the high-level sensor transmits a controlling signal to stop the chemical-liquid refilling process.
However, since the chemical liquid is caustic, the chemical liquid easily causes malfunctions in the sensors. In particular, when the malfunctions occur in the sensor because of erosion by chemical liquids, the refilling chemical liquid may easily raise above the high level without being noticed. Once the refilling chemical liquid reaches a level that is closer to the exhaust pipe, the exhaust pipe easily draws out the chemical liquid. Therefore, malfunctions readily occur in the exhaust apparatus and the exhaust pipe and workers may also be injured.